As digital broadcasting is paving the way for its extensive spread, a broadcasting station transmits both main audio-visual (AV) contents and enhanced service data, which may be linked to the main AV contents to provide information and services or may be separately provided for other purposes.
However, a video display device in each home may unlikely receive broadcast signals directly through air under a current broadcasting environment. Rather, most of cases, a video display device in each home is connected to a broadcast receiving device to display uncompressed audio-visual contents that the broadcast receiving device provides.
Additionally, the broadcast receiving device receives contents from a server (called a Multichannel Video Programming Distributor (MVPD)). The MVPD receives a broadcast signal from a broadcasting station, extracts contents from the received broadcast signal, converts the extracted content into signals having a proper format for transmission, and provides the converted signals to a broadcast receiving device. During these processes, the MVPD may exclude extracted enhanced service data or may add another enhanced service data, so that the broadcasting station may serve to provide AV contents but may not provide enhanced services led by the broadcasting station.
Since the broadcast receiving device extracts main AV data from signal received from the MVPD and provides only uncompressed audio-visual data to a video display device, only enhanced services provided from the broadcast receiving device not the video display device are available. Furthermore, the broadcasting station may not provide enhanced services led by itself.
Additionally, even when the broadcasting station provides enhanced services through wireless channels, the enhanced services may not be provided enough due to bandwidth limitation.